1. Field of the Invention
The present invention relates generally to a cruise control system for automotive vehicles. More specifically, the invention relates to a system for automatically controlling the vehicle speed so that the vehicle runs at a desired speed set by the driver of the vehicle.
2. Description of the Prior Art
In recent years, various cruise control systems for automotive vehicles have been proposed. Such cruise control systems can automatically adjust the vehicle speed by operating switches or the like so that the vehicle can run at a set constant speed. For example, when the vehicle is running on a highway, such systems are convenient to the driver since he or she needs not always step on the accelerator pedal in order to cause the vehicle to run at a desired, constant-speed.
The cruise control system may be used for vehicles with either manual or automatic transmissions. In the case of such a conventional system incorporated in the manual transmission, if the system is operated while the vehicle is moving at a low-speed or at a gear position in which high torque is required, such as first or second gear, noise and fuel consumption are increased, since high engine speed is maintained. On the other hand, in the case of such a conventional system incorporated in the automatic transmission, the system can not only be operated while the automatic transmission is set in the normal driving mode, i.e. a drive range (D range), but also in reverse mode (R range), or in a first or second gear by which engine braking or high torque is obtained. If this system is operated while the transmission is set in the first or second gear, a great deal of noise tends to be produced during driving, and fuel consumption is increased.